Objective: Next-generation imaging with prostate-specific membrane-antigen Positron Emission Tomography/Computed Tomography (PSMA PET/CT) has emerged as an imaging modality offering high diagnostic accuracy and prognostic biomarkers in the primary staging of prostate cancer (PCa). Among these, PSMA-positive tumor volume (PSMA-TV) may carry prognostic significance but has been poorly investigated in patients receiving radical-intent radiotherapy (RT). Methods: Patients with biopsy-proven unfavorable intermediate-to-high-risk PCa staged as non-metastatic (T1-4 N0-1 M0) at [68 Ga]PSMA-11 or [18F]PSMA-1007 PET/CT before definitive RT plus androgen deprivation therapy (ADT) at our Institution (2019–2024) were retrospectively recruited. Following RECIP criteria, semi-quantitative PET parameters extracted were: maximum and mean standardized uptake value (SUVmax and SUVmean), PSMA-TV, and total lesion PSMA uptake (PSMA-TL) [PSMA-TV*SUVmean]). We assessed the association between PET-derived semi-quantitative parameters and clinical outcomes, including time to treatment failure (TTF) and PSA response. Inverse probability of treatment weighting (IPTW) was adopted to address confounders, namely, initial PSA, ISUP score, T stage, and N stage. Results: Among 145 patients recruited, median age was 76 years and median initial PSA 8.9 ng/mL. Most patients had ISUP grade ≥ 3 (39.3%), and 28.3% presented with nodal involvement at staging. Concurrent androgen deprivation therapy was administered in all patients, and the most common duration was 12–24 months (60.7%). The median follow-up was 20.5 months. While unadjusted analyses showed no significant association between PET parameters and treatment outcomes, IPTW-adjusted survival analysis revealed that high PSMA-TV was significantly associated with shorter TTF (p < 0.05). Other PET-derived metrics were not predictive of outcomes. Conclusion: Our findings highlight PSMA-TV as an independent predictor of treatment failure following definitive RT in PCa, supporting its potential role as a risk-stratifying biomarker, paving the way for individualized therapeutic strategies. Prospective validation is warranted to confirm its clinical utility and guide future radiotherapy personalization.
Baseline PSMA tumor volume as a prognostic marker in radical radiotherapy for prostate cancer: a propensity score-weighted retrospective analysis
Lanfranchi F.;Belgioia L.;Bauckneht M.
2025-01-01
Abstract
Objective: Next-generation imaging with prostate-specific membrane-antigen Positron Emission Tomography/Computed Tomography (PSMA PET/CT) has emerged as an imaging modality offering high diagnostic accuracy and prognostic biomarkers in the primary staging of prostate cancer (PCa). Among these, PSMA-positive tumor volume (PSMA-TV) may carry prognostic significance but has been poorly investigated in patients receiving radical-intent radiotherapy (RT). Methods: Patients with biopsy-proven unfavorable intermediate-to-high-risk PCa staged as non-metastatic (T1-4 N0-1 M0) at [68 Ga]PSMA-11 or [18F]PSMA-1007 PET/CT before definitive RT plus androgen deprivation therapy (ADT) at our Institution (2019–2024) were retrospectively recruited. Following RECIP criteria, semi-quantitative PET parameters extracted were: maximum and mean standardized uptake value (SUVmax and SUVmean), PSMA-TV, and total lesion PSMA uptake (PSMA-TL) [PSMA-TV*SUVmean]). We assessed the association between PET-derived semi-quantitative parameters and clinical outcomes, including time to treatment failure (TTF) and PSA response. Inverse probability of treatment weighting (IPTW) was adopted to address confounders, namely, initial PSA, ISUP score, T stage, and N stage. Results: Among 145 patients recruited, median age was 76 years and median initial PSA 8.9 ng/mL. Most patients had ISUP grade ≥ 3 (39.3%), and 28.3% presented with nodal involvement at staging. Concurrent androgen deprivation therapy was administered in all patients, and the most common duration was 12–24 months (60.7%). The median follow-up was 20.5 months. While unadjusted analyses showed no significant association between PET parameters and treatment outcomes, IPTW-adjusted survival analysis revealed that high PSMA-TV was significantly associated with shorter TTF (p < 0.05). Other PET-derived metrics were not predictive of outcomes. Conclusion: Our findings highlight PSMA-TV as an independent predictor of treatment failure following definitive RT in PCa, supporting its potential role as a risk-stratifying biomarker, paving the way for individualized therapeutic strategies. Prospective validation is warranted to confirm its clinical utility and guide future radiotherapy personalization.
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